 We are going, we have studied different hydrocarbon compounds and that hydrocarbon compounds so different functional group we have studied and that functional group, first text which we are going to study is the homologous series, homologous series is what we are going to study, homologous series where hydrocarbon come out to the carbon compounds they are attached to the same function. But the number of carbon atoms they release or the number of carbon atoms change accordingly and what some people women say in this homologous series. Today we are going to study the homologous series of acid in the first example if we will take that is this is the Methanoic acid. We know that methane which consists of only one carbon atom. Here for, here I understand that I have taken the different elements of the clay models which are having a different clay. So that we can identify the different elements for carbon I have chosen the red color for hydrogen it is yellow and for oxygen it is blue color. So now suppose if we want to study the Methanoic acid. So here you can observe this carbon atom one carbon atom it is attached with the two oxygen and two hydrogen atoms. So this is the one carbon atom where we can study the Methanoic acid the formation of this Methanoic acid. Where the acid functional group where only one single carbon atom is attached to the COH group. Second example I am going to take in the homologous series is the Methanoic acid Ethane. We know that the Methanoic acid is an acid which consists of two carbon atoms. If we will study this example here I have taken the two carbon atoms. Out of these two carbon atoms one carbon atom consists of its functional group that is C, double bond O and this O and H. And here as simple as I can put it as to this one carbon atom. Third example if we will take that is the Methanoic acid. If we will study one by one the number of carbon atoms is increased in each and every structure. So in propane acid there is a presence of three carbon atoms out of these three carbon atoms. One carbon atom is attached with the function group where the C double bond O H and other two functional group. Our other two of carbon atoms they are the alkene group where the two hydrogen atoms are connected to this. So homologous series is a series where the carbon atoms are the function group which is attached to the carbon atoms that will remain same. But just the number of carbon atoms which we are going to add in each series. So this is the best example or with this clay model you can easily understand how we can form the different structures from this clay model. And how we can attach the different carbon atoms and there is a combination of different functional group. Thank you.